Effects of methamphetamine on the isolated rat phrenic nerve-diaphragm preparation

Low concentrations of methamphetamine facilitated twitch, while higher concentrations produced dose-dependent blockade of twitch indirectly elicited. Methamphetamine facilitated twitch elicited by direct stimulation; These findings suggest that methamphetamine-induced enhancement in physical endurance and performance in moderate doses, and muscle weakness at high doses, may be attributed to drug effects at a peripheral site of action.